The following is some compiled information from Susanne and me regarding different acids that are used for chemical peeling. Starting with the very superficial peels:

BETA HYDROXY ACIDS
Beta Hydroxy Acid or BHA is a derivative of aspirin and is often used in skin care products to accelerate skin cell turnover and help clear pores. It can penetrate more deeply than Alpha Hydroxy Acid and is gentler.

Beta Hydroxy Acid is salicylic acid. This occurs in nature in sweet birch and in wintergreen leaves. Its effect on the epidermis and upper dermis are similar to those of Retin-A, but with less irritation. It is soluble in oil and can exfoliate oily skin areas, even within oil-rich pores. Therefore, it has a beneficial effect on acne, pigmentary disturbances, and sun-damaged skin. Because it does exfoliate, use of sun protection is needed.

Test any product that contains a BHA on a small area of skin before applying it to a large area. If you use cosmetics with BHAs and experience skin irritation or prolonged stinging, stop using the product.

ALPHA HYDROXY ACIDS
Alpha-Hydroxy Acids or AHA is a compound found naturally in many common fruits and other foods. The principal AHA is glycolic acid which is found in sugar cane and sugar beets. Other AHAs include lactic acid from dairy products and malic acid from fruit. Glycolic acid is the most skin-active AHA; and its primary action is to accelerate shedding of abnormal cells in the topmost layers of the skin by decreasing their cohesiveness. Continued use of glycolic-acid-based products may result in a normalized, more compact top layer of the epidermis. This makes the skin smoother. Additionally, it helps to remove comedones (blackheads); and, like retinol, it helps to restore the barrier function of the skin, thereby helping naturally to increase its own moisture content. It also leads to increased collagen production in the upper dermis, resulting in reduction of fine lines. Glycolic acid also has an anti-inflammatory effect and is able to enhance the effects of other topical agents, such as hydroquinone and salicylic acid. It is well-tolerated by many people, but it can cause irritation and stinging in some. It can make the skin more sensitive to the effects of the sun’s UV rays; therefore
use of effective sunscreen is essential.

The main benefits of alpha hydroxy acids come from its ability to exfoliate skin. Removal of the outermost layer of the skin stimulates the cells in lower layers to grow and divide, causing the skin to thicken and thus diminishing visible signs of aging. The more you exfoliate, the more cell divisions you have occurring in the lower skin layers. Good thing!

The most important precaution to take when using alpha hydroxy acids is to know the percent and pH level of the product. The ideal pH is 3.0-3.5, any lower and the product may be too acidic; any higher and the product's exfoliating benefits may be nullified. Even at lower levels, though, some alpha hydroxy acids can be irritating, depending on how sensitive your skin is. Mandelic acid is the recommended AHA for those with sensitive skin since it is the most non-irritating. Also, darker skin types should avoid most alpha hydroxy acids due to the risk of hyperpigmentation. Hyperpigmentation will occur in darker skin if it becomes irritated or inflamed. Those with a skin type which tans easily or rarely burns through skin types which always tan or never burn, should be especially careful and avoid possibly irritating products. Because alpha hydroxy acids peel away the tough outer layers of the skin, the newer and younger skin is more susceptible to the suns UV rays
.
Listed below are some of the realistic vs. unrealistic goals of chemical peels. This may be helpful if you are trying to decide if this procedure is right for you.

Realistic Goals of Chemical Peels:
Chemical peels can correct (sun) damage.
They can reduce mild scarring.
You can experience a reduction or eradication of your wrinkles.
Improvement of dark skin discoloration is possible.
Chemical peels can remove excessive or stubborn blackheads.
The peel may temporarily reduce excessive skin oils

Unrealistic Goals of Chemical Peels:
It cannot remove or reduce the appearance of blood vessels on the skin.
It is impossible to truly change pore diameter. However, by removing blackheads, the pores may actually appear less pronounced after treatment. This is not a procedure to get rid of keloidal types of scars
Chemical peels are not a facelift. This is typically not appropriate for improving dark skin discoloration in people of color (Asians, African Americans, Caucasians of Mediterranean extraction, Hispanics, etc.)
The glycolic acid peels (ranging from 70%-99% glycolic acid compound) and the beta-hydroxy acid (salicylic acid) peels (ranging from 20%-30% salicylic acid in a microsponge delivery system) are among the most effective chemical peels.

Glycolic acid peels work by diminishing the cohesion of the skin cells (corneocytes) at the innermost levels of the surface layer of the skin (stratum corneum), by stimulating this layer of skin in its renewal process, increasing skin thickness, and promoting the formation of new epidermis and new dermal collagen. This process will result in skin shrinkage, reduction of wrinkling and "crepe-paper-like" skin, softening of "crow’s feet," and often helping to lighten hyperpigmentation.

The salicylic acid peels (BHA)or Beta-Lift peels are effective in lifting the topmost layer of skin by dissolving the "glue" (desmosomes) which binds it to the underlying epidermis, triggering a "burst" of cell division which accelerates skin cell production and shedding. Its developer, Douglas Kligman, M.D., Ph.D.(who is the son of Albert Kligman, M.D., Ph.D., the founder of Retin-A), developed it for the cosmetic treatment of sun-damaged skin, hyperpigmentation (including melasma, "liver" or "age" spots, and freckles), superficial lines, and "weathered" or rough skin. The salicylic acid peels are often more intense than the glycolic acid peels.

If you are currently taking or have taken Accutane within the past six months, you are not a candidate for chemical peels. Patients with healing wounds from recent surgery, patients with active herpes simplex (fever blisters or cold sores) on their face, patients who have had radiation therapy to their face (or to the area which they wish to have peeled), or patients who have had cryotherapy in the past month should not have a chemical peel. A tendency toward hypertrophic or keloidal scarring may also make you not a good candidate for a peel. It is essential that you use very effective
photoprotection after a peel; thus, if you are unwilling or unable to do so, you should not consider having a chemical peel.

THE SUPERFICIAL CHEMICAL PEELS:

Very Superficial:
This really isn’t a true peel, more of an exfoliation. The most superficial layers of the stratum corneum (at the top of the epidermis) is removed or thinned during exfoliation. Most chemical peels have a preoperative regimen of using exfoliating agents such as Renova, Tazorac or a strong glycolic acid cream for 2-4 weeks prior to the actual procedure. This helps the chemical peeling agents penetrate more deeply and evenly. The use of these exfoliants also have the obvious beneficial properties of smoothing out thickened rough areas, helping self tanners go on more evenly and helping other
skin rejuvenation products reach deeper tissues. Additionally, there has been good evidence that vitamin A exfoliants can help stimulate collagen deposition.

Superficial:
Superficial chemical peels remove skin through a portion or the entire epidermal layer. These are the “refreshing” forms of skin peels. They can also help with reducing the appearance of very mild blotchy skin discoloration, remnant acne discoloration and help cleanse the pores. This is the most common form of peel that you would find performed in a spa or by an aesthetician. Higher levels of glycolic acid are typically used by physicians falling toward the Medium range.

Resorcinol peels can cause a slightly deeper peel much like sunburn.

Superficial peels do not interfere with your normal everyday activities, so you need not take time off work or stay at home out of the public eye. In other words, these peels are a full treatment program over several months. The peels could be performed weekly, as they contain a concentration of ingredients which are far higher than those sold over the counter or applied by beauty therapists. It is also important not to abandon this treatment prior to having had the full course, because the treatments are cumulative and the previous one enhances each subsequent treatment. The ideal number of treatments is six. Several days after each of the peels, flaking or light peeling of the skin will occur. Subsequent weekly peels have their strength and length of application adjusted according to your individual previous response.

Active ingredients used in mild to moderate chemical peels: Glycolic Acid (AHA), Salicylic Acid (BHA), Lactic Acid, Jessner’s Peel (a combination of salicyclic acid, resorcinol and lactic acid mixed in ethanol), Resorcinol, TCA (Trichloracetic Acid) TCA is used in a variety of peeling regimens such as AccuPeel and the Obaji Blue Peel.

Medium Peel:
This type of peel goes through the epidermis, down into the upper most portion of the dermis known as the papillary dermis. Medium peels are the level when complications are more likely to start. In addition to the pre-peel use of exfoliants, the use of a skin bleaching agent, such as 4% hydroquinone, and a broad-spectrum sunscreen a month prior to the procedure, may be added for more aggressive forms of these peels, or for patients who already suffer from some form of skin discoloration. Inflammation from this level peel may temporarily produce an increase in skin tone. Medium peels are typically not appropriate for people with darker skin tones or of ethnic background again due to the risk of irregular pigmentation following the procedure.

Dealing with infection preventatively is important here. For non-buffered glycolic acid and more commonly TCA peels, the use of antiviral medication (herpes prevention) started before the peel is performed is very helpful. The use of antibiotics is sometimes also used. It is absolutely CRUCIAL that you not pick at the peeling skin during the healing phase. This is a sure way to end up with an infection and long lasting problems such as scarring or skin discoloration. Often the use of emollients during the first few days is incorporated in addition to the continued use of sunscreen, and a very mild cleansing agent. Make-up is often avoided until the skin has fully peeled away.

Examples of chemicals used for a medium peel include: Glycolic Acid 70%+ (non-buffered), TCA 35-70%, combination peels such as solid CO2 followed by medium strength TCA, and glycolic acid followed by TCA.

Prepping the skin prior to all peels for at least one month with a tretinoin and hydroquinone or the daily use of an AHA is CRUCIAL to having an un-eventful and successful peel. This will allow for an all over even peel with fewer chance of hyper-hypo pigmentation and will allow the acid to work more efficently. You will need to stop all actives such as your tretinoin/hydroquinone, or AHA's at least 4-5 days prior to your peel or the peel may go to deep thus causing scarring or hyperpigmentation.

Most Chemical Peels purchased for home use come with complete instructions. Please read and re-read before doing your peel and if doing a light to light-medium peel, make sure that you have allowed your self enough days set aside for your "downtime"....time that you will not want to be seen in the public eye. With most AHA's, BHA and low percent (under 50%) or so, there really is no down time. With the Jessners and TCA's, depending on strength, pH, skin sensitivity, and time left on the skin, you can and should expect a good 7 days or more for all peeling to stop.

PLEASE NOTE: THERE IS NO FROST WITH THE BHA, AHA, GLYCOLIC PEELS...MOST GLYCOLICS NEED TO BE NEUTRALIZED WITH BAKING SODA AND WATER. Best to have a sink ready to go once you're ready to stop the peel.

It is ESSENTIAL that one do a patch test about 48 hrs. prior to the actual peel! This is especially true with TCA. For instance, if you are doing a face peel, do a patch test on either side of your forehead, and either side of your cheeks as the areas will react differently. Use a q-tip and do the patch test near your hairline. That way the patch area is easily covered with Vaseline or Aquaphor during the actual peel. For good results and a medium-depth peel, you need to achieve a light frost. Apply the peel in layers until you have that frost.

For instance, when I peel my chest, I do four different patch areas. I applied two layers to one side with a light frost, and three layers to the other with an opaque, fairly substantial frost. I decided to err on the side of caution and just did two layers for the actual peel. Got tremendous results!

TCA is self-timing and self-neutralizing. Wait about 4-7 mins between layers to judge the frost. Also, the burning will begin to subside when that layer is complete. OTOH, lactic and glycolic peels are NOT self-timing and must be neutralized with a baking soda and water mixture to terminate the process.

If you are not an experienced peeler, then I suggest that you start with either lactic or glycolic acid. Start with two minutes and work your way up. There should be little downtime from glycolic and almost none with lactic. You may have a few patches that look like rugburn for a couple of days, but they are usually gone by the fourth or fifth day. In contrast, a TCA peel WILL result in downtime of 5-7 days and you simply cannot cover the peeling skin with makeup......nor would you want to do so. You will need to plan to hide from the world for about five days if you are at all self-conscious about your appearance. On the day of the peel, please make sure that you have everything you need according to your peel instructions.

APPLICATION: Cleanse and remove all makeup, lotions, creams and sunblock from your skin..

DEGREASE: This is removing any left over residue on your face along with any surface oils. You can use alcohol, or acetone. Wipe your face or area to be peeled with a cotton ball or gauze pad until the pad comes back clean....let dry. (Note: I really do an over-kill with prep. I degrease with acetone (the Home Depot type, not nail polish remover), take a warm soapy shower, pat dry, wipe with alcohol, and then start the peel).

APPLY CHEMICAL: It is best to use a small glass, or porcelain bowl to pour some solution into rather than "tipping" the bottle...pour a small amount as you can always add more. Most find that using a fan brush best for even application on the neck, chest, arms and legs and doesn't use up so much product, or you can use a cotton ball or gauze square. I personally prefer a tightly-woven gauze square (PRESS the gauze in for more even and deeper penetration) or the little triangular cosmetic sponges for my face, along with a q-tip to outline areas such as eyes, mouth, etc.

Dip your applicator in to your bowl and allow any excess solution to drip back into the bowl or press up against the side of the bowl so as not to over drench and apply a too-heavy layer.

We have found it best to apply in sections...one at a time. So, start with swiping your FOREHEAD first...next the CHIN (as these are the most resistant areas) then the TOP of your nose, then ABOVE YOUR LIP....CHEEKS, SIDE of face and the sides and tip of nose last. Any type of peel will burn like the Devil, so have a cooling source on hand.......a hair dryer on cool, a fan, or some of us have been known to stand naked in front of an open refrigerator door.

When the peel is finished, thoroughly rinse with tepid water first. If it's lactic or glycolic, then neutralize with a baking soda & water mixture, let it sit for about two minutes, and then wash it off. I like to moisturize with my emu oil after everything is finished. Don't get obsessed about the baking soda/water proportions.......it's not rocket science. The soda will begin to precipitate out when the solution is saturated, so really the important thing is the Nike way--"just do it". Some folks put their soda/water mixture into a sink and rinse there, but I tend to get it all over the floor, and just prefer to do mine in a shower with a large glass of the soda/water mixture.

The above is by no means a complete guide, but was a effort to begin to organize information that is scattered all over the forum. Many thanks to Susanne for doing most of the work. We miss you, Sus!

DEEA......o.k., I added your suggestion to the Sticky. If you or anyone else have suggestions for corrections or additions, please PM them to me to avoid cluttering the thread. I'm by no means an expert on the subject, and the knowledge base here is a cooperative effort on the part of ALL our members.